Prostate testing – peace of mind or panic?

Even though most men know that ageing increases the probability of acquiring prostate cancer (particularly beyond 65), there has been a long-standing reluctance to raise the subject with their family doctor.

That’s partly explained by denial, the subconscious rationalisation that if you don’t think about it it won’t happen. But it’s also to do with the historical diagnostic procedure – what was clinically termed a Digital Rectal Examination (DRE) or, less euphemistically, a probing finger up your bum. For most men, the prospect of a DRE is more terrifying than the cancer itself.

Notwithstanding this reluctance, prostate is the most diagnosed of all cancers among Australian men. In 2022, over 24,000 new cases were diagnosed, representing more than a quarter of all new male cancer cases and 3,507 deaths recorded accounting for 13% of all male cancer deaths.

Yet, despite the fact that intruding fingers have been completely superseded since 2016 by the  far less invasive PSA (prostate specific antigen) blood test, there is no national screening campaign for prostate cancer in stark contrast to bowel cancer, breast cancer and cervical cancer,

Why not?

The answer is that, despite a 50% decline in prostate cancer deaths since the introduction of PSA testing, it is a controversial test. You see PSA doesn’t actually test for cancer, just for indications that cancer might be present.  A heightened PSA could simply indicate an enlarged prostate, or an infection or nothing at all. Some argue that high PSA readings perversely lead to an over-diagnosis of prostate cancer and overtreatment with consequent serious side-effects.

Conversely, 15% of men with low PSA can have cancer. (false negatives).

Until recent times, a heightened PSA reading would trigger a biopsy, commonly carried out through the rectum and, while uncomfortable rather than painful, often perversely itself causing septicaemia.

Biopsy samples may identify the presence of cancerous cells but that is not in itself a sufficient indicator of whether that would develop into full-blown cancer. Based on a precautionary principle, this has resulted in a high rate of radical prostatectomies – removing the entire prostate gland, with unintended consequences such as erectile disfunction in 90% of cases and incontinence to a lesser degree. Against this, data suggests that only one in 45 operations actually results in a life being saved thanks to PSA testing.

Measured against this outcome, the five year survival rate for most prostate cancers is very high.  96% of men diagnosed with prostate cancer between 2013 and 2018 survived at least five years. In fact, far more men die with prostate cancer than from prostate cancer. That leads many health professionals to argue that universal screening simply isn’t warranted. The counter argument points out that despite falling mortality rates, the ageing of our population more than compensates for any reductions in age-adjusted mortality rates so that the absolute numbers of deaths from prostate cancer will continue to rise.

So what should a concerned senior gentleman do?

Well, the Royal Australian College of General Practitioners (RACGP) and the Prostate Cancer Foundation of Australia (PCFA), have just released draft revised guidelines which recommend that GPs offer two-yearly testing to all men aged 50-69. (That extends to age 40 if there is a family history or if you are of sub-Saharan or Aboriginal/Torres Strait Islander heritage.)

Apart from the new guidelines on testing (which include world first measures by testing from 40 for men with heightened risk and testing after 70), our approach to managing detected cancer has also changed.

Instead of commissioning biopsies as a first line of confirmation, which are prone to hitting or missing the affected area, doctors now recommend that patients undergo a non-invasive MRI.  The advantage of MRI is that it not only detects any lump present but it accurately directs the urologist to perform a biopsy, if warranted, in the precise location of the lump.

This significantly reduces the rate of unnecessary biopsies.

But it’s also the approach to treatment that has changed. Instead of automatically prescribing chemical or radiation therapy, the guidelines encourage Active Surveillance by which patients are closely monitored to ensure medical intervention is only introduced in response to cancer progression.

That still leaves a good deal of uncertainty in the chain of prostate health management.

The good news is that there are promising alternative tests coming down the pipeline that may be more reliable than the PSA.

Research recently published in the journal Cancer Research suggest that early-stage prostate cancer can be detected using a simple urine test.

The researchers created digital models of prostate cancer by analysing mRNA activity in thousands of individual tumour cells classified by their cancer grade and location. They then used artificial intelligence to identify proteins that could act as potential biomarkers.

These biomarkers were then tested in nearly 2,000 patients and found to be more reliable predicators of cancer than PSA readings.

Also currently, British researchers are trailing saliva tests intended to detect genetic predispositions for prostate cancer which could then refocus PSA testing on high-risk individuals.

The qualifying footnote is that these tests are in the very early stages of validation, and it will be several years before they might be applied more broadly than clinical trials.

In the meanwhile, the current system of testing based on risk factors, diagnosis by a combination of PSA, MRI and location directed biopsies, and Active Surveillance with treatment only where warranted is a much better-balanced regime than our previous inclination to jump to radical surgery.

And as a bonus, you don’t need to contemplate an inquisitive finger up your bum.

Dr John Levin